^(99)Tc^(m)-DOTA-G3NGR SPECT显像靶向评价抗血管生成药物早期疗效的初步实验研究

Preliminary experimental study of^(99)Tc^(m)-DOTA-G3NGR SPECT imaging targeting to evaluate the early efficacy of antiangiogenic drugs

目的:探究^(99)Tc^(m)标记NGR对CD13阳性表达的肿瘤小鼠模型进行SPECT显像,以期为靶向评价抗血管生成药物早期疗效提供一种直观的影像学方法。方法:用^(99)Tc^(m)标记,制备环形DOTA-G3NGR(DOTA-GGGNGRC),再分别以HT-29人结肠腺癌(CD13表达阴性)和HT-1080人纤维肉瘤(CD13表达阳性)细胞按106/只接种于裸鼠右侧腋下建立荷瘤小鼠模型,以200μCi/只通过腹腔注射^(99)Tc^(m)-DOTA-G3NGR行SPECT显像,采用感兴趣区技术(ROI)对图像进行半定量分析,选择肿瘤作为靶组织(T),对侧肌肉组织作为非靶组织(NT),统计ROI内的总放射性计数计算T/NT比值。结果:DOTA-G3NGR分子量1107.2,^(99)Tc^(m)-DOTA-G3NGR标记率为85%放射化学纯度(radiochemical purity,RCP)达95%以上(97.30±0.76)%(n=4);经室温和37℃(10%FBS,5%CO_(2))条件下,6 h内RCP均在90%以上。HT-1080移植瘤最大T/NT值可达4.23±0.53,且高峰时间出现在注射后4小时,而HT-29移植瘤T/NT值约1.20±0.15,且无明显峰值。通过给予抗血管生成药物(0.5 mg/kg,连续7天后),再注射^(99)Tc^(m)-DOTA-G3NGR显像结果显示HT-1080移植瘤T/NT值出现明显的降低但仍高于HT-29移植瘤(P<0.0001,P<0.0001,P=0.0306,n=5)。结论:^(99)Tc^(m)-DOTA-G3NGR对CD13具有良性的靶向性和较高的T/NT值,在靶向评估抗血管生成药物早期疗效方面具有潜在应用价值。

Objective:^(99)Tc^(m) labeled NGR was used to perform SPECT imaging on CD13-positive tumor mouse models in order to provide an intuitive imaging method for targeted evaluation of the early efficacy of antiangiogenic drugs.Methods:The cyclic DOTA-G3NGR was prepared by activated ester method,purified by HPLC and labeled with^(99)Tc^(m),then purified by dialysis tube(MWCO:500-1000).The labeling rate and in vitro and in vivo stability of the labeled compound were determined.HT-29(negative for CD13)and HT-1080(positive for CD13)cells(10^(6) cells/mouse)were inoculated into the right armpit of nude mice to establish a tumor bearing mouse model,and^(99)Tc^(m)-DOTA-G3NGR was injected into the abdomen of 200μCi(0.7 MBq)/mouse to perform SPECT imaging.The region of interest technique(ROI)was used for semi-quantitative analysis of the images.Tumor was selected as target tissue(T),and contralateral muscle tissue was selected as non-target tissue(NT).The T/NT ratio was calculated by counting total radioactivity in ROI.Results:the molecular weight of DOTA-G3NGR was 1107.2,the labeling rate of^(99)Tc^(m)-DOTA-G3NGR was 85%.Under the conditions of room temperature and 37℃(10%FBS,5%CO_2),the RCP was above 90%within 6 h.The maximum T/NT value of HT-1080 transplanted tumor was 4.23±0.53,and the peak time was 4 hours after injection,while the T/NT value of HT-29 transplanted tumor was about 1.20±0.15,and no obvious peak value.After being given antiangiogenic drugs(0.5 mg/kg for 7 days)and then injected with^(99)Tc^(m)-DOTA-G3NGR imaging results showed that T/NT value of HT-1080 grafts decreased significantly but was still higher than that of HT-29 grafts(P<0.0001,P<0.0001,P=0.0306,n=5).Conclusion:^(99)Tc^(m)-DOTA-G3NGR has a benign targeting effect on CD13 and a high T/NT value,which has a potential application value in evaluating the efficacy of anti-angiogenesis drugs.